Resistance device



April s, 1941.

J. W. WEST RES ISTAHCE DEVICE Filed June ll, 193B gli! M im' 22 /NVE/VTOR By J. W WEST Patented pr. 8, 1941 RESISTANCE DEVICE John W. West, Woodside, N. Y., assigner to'Bell Telephone Laboratories, Incorporated, New

York, N. Y., a corporatie n of New York Application June 11, 1938, Serial No. 213,200

8 Claims.

fIhis invention relates to resistance devices and more particularly to high current con-trolling de- Vices."

In many electrical speech transmission systems involving apparatus supplied with electrical energy either from a battery source or a direct current or alternating current power line, it is essential to regulate the current supply in order that uctuations in the source will not materially aifect the operating characteristics of the apparatus. It is common practice to introduce a. resistance device or rballast resistance in the operating circuit to maintain the current constant regard-less of the voltage variations Within a, certain range. It is desirable in certain installations that the current capacity of the apparatus be maintained at a uniformly high level to satisfy exacting operating conditions.

An object of this invention is to facilitate the assembly of a resist-ance device for maintaining constant current regulation of high capacity Within a definite voltage range.

IAnother object of the invention is to prevent distortion of :the multiple elements in a resistance device of high current capacity.

A further object of the invention is to insure accurate alignment of the multiple elements by an efdcient mounting assembly of low cost.

In accordance with one aspect of the invention, the resistance device comprises an enclosing vessel and a mounting assembly for supporting a, plurality of parallel illament sections or strands therein. The mounting assembly includes a plurality of frame supports secured to the vessel which carry a pair of spaced insulating discs between Which the mul-tiple strands of expansible laments are arranged and secured to the frame supports.

Since the devi-ce may be mounted in various positions, it is desirable that the expansible laments lare not subjected -to undue distortion caused by expansion and contraction under operating conditions. This is avoided in accordance with this invention by supplementing the main supports of the filaments with an intermediate spacer which maintains the laments in uniform relation .and insures accurate alignment of the laments by limiting the lateral movement of the strands.

In accord-ance with 'a specifi-c aspect of the invention the intermediate spacer of the mount comprises a vertical mica strip having a serrated edge t'o space the stra-nds -in parallel relation and 'the strip is locked in position between' the end discs of the mounting .frame by end prov port wires i6 and I1.

These and other features of the invention will be more clearly understood :by referring to the following detailed description and the accomrallying drawing:

Fig. 1 is a perspective view of a complete device made in accordance with this invention with a portion of the enclosing vessel broken away to show the Internal structure;

Fig. 2 is a view in elevation of the mount of this invention supported on a stem;

Eig. 3 is a side view of the mount of Fig. 2; and

Fig. 4 is an exploded view in perspective of the mount showing the details of construction.

Referring to the drawing and Fig. 1 particularly, the resistance device of this invention is embodied in an evacuated glass enclosing vessel of elongated form an inwardly projecting stem Il terminating in a press I2. A plurality of leading-in wires i3 are sealed in the press and are connected externally to an Edison type base I4 secured to the stem and oi the vessel. A metallic collar I5, formed of two sections,

is clamped securely to the stem II and carries a plurality of upright frame members or wires I6, I 1, I8, and I9 which are arranged in spaced relation with the wires I6 and Il in one plane and the wires I8 and I9 in a plane at right angles thereto. These support wires are braced and held in their specified relation by transverse spacer discs 20 and 2|, preferably of mica, although other suitable insulating materials may be employed for this purpose. 'Ihe discs are secured to the supports by metallic eyelets 22 which are crimped to the discs and welded to the wires.

The disc '20 is attached to the wires at their uppermost ends, while the disc 2I is attached to the wires adjacent the press I2. This arrangement forms a rigid frame structure which is capaIble of withstanding vibrations or shocks which might cause breakage of the assembly or the enclosing vessel.

A plurality of parallel expansible filament sections or strands `23 are strung -between the sup- These sect-ions, preferably iormed of spiral tungsten for a lamp of high current capacity, are arranged between the end spacer discs 20 and 2| and extend diametrlcally across the axis of the device in a plane coincident with the support wires I6 and I'I. As shown in the drawing a number of the laments 23 are provided to obtain the required capacity rating for the desired device. Of course, the specic number of filament sections shown are not essential to the general aspects of this invention. Since the expansible filament sections 23 are quite brittle when cold and are easily distorted when heated to their operating temperature, it is desirable to oiset these defects in order to secure a long life for the lamp and freedom from mechemical diiliculties due to breakage or the iliaments and electrical detects, such as short circuits caused by distortion oi the strands.

In accordance with this invention, the parallel filament sections are supported at the center by a vertical spacer 24, formed oi metal or insulating material, such as mica, which is locked in oilset position between the end mica discs Il and 2l by projections 2l on the ends of the strips, which are seated in slots 28 in the discs 2D andai. The mica strip 2d is also provided with a serrated edge in the form of slots 2l which receive the center portions of the lament sections 23, the spiral iilaseated in the enlarged ridge at the end of th slots. This arrangement rigidly supports the center portion of the i'llament sections and holds the sections in lateral relation so that distortion or sagging is prevented.

The lower disc 2l is provided with a plurality of apertures 28 through which the leading-in wires Ib extend so that their ends are above the disc il. The pairs of wires on opposite sides of the vertical spacer 28 are then connected to the frame supports it and il by bridging wires 29 and 363, respectively. This arrangement connects all the filament sections in parallel to obtain a high capacity current rating for the device. The separate pairs of leading-in wires are connected to the respective terminals on the base i4 as previously described. 1

The construction forms a compact mount in which the upright frame wires are rigidly assembled and held in spaced relation by the end mica discs and the vertical spacer 2S is rigidly locked in position between the end discs to provide a mount which may be easily assembled as a unit apartfrom the vessel in which it is to be installed. Furthermore, the vertical spacer also forms va barrier between the separate pairs of leading-in wires in the lower mica disc 2l so that a conductive path is not easily formed by evapo-4 rated metal deposited on the disc 2i between the leading-in wires. This arrangement materially increases the insulation resistance of the device and insures a longer operating life.

While the invention is described in connection with its use in a ballast resistance for controlling current, it is, of course, understood that its use is not limited in this respect, since it may be used in other elds in which multiple iilaments are mounted in a unitary assembly, such as a light source in commercial photography, resistance elements, heater type elements for therapeutics and iloodllghting devices.

, Furthermore, the specific details of assembly heretofore described are not to be construed as constituting the only manner of obtaining the results of this invention, since various modications may be made to achieve the concepts of the invention and such modications are deemed to come within the scope of the appended claims.

. What is claimed is:

l. A resistance device comprising an enclosing vessel, a frame structure supported therein including insulating members spaced in parallel relation, multiple resistance elements extending across said frame and parallel to said insulating members, and a vertical insulating spacer held in position by and betweensaid members, said spacer having slots in one edge, said elements being supported intermediate their ends in said slots.

2. A resistance device comprising a vessel, a

frame structure supported therein including insulating discs apart in parallel relation, a plurality oi parallel lmetallic iilaments extending diametrically across said frame structure, and an insulating member engaging. said laments intermediate their ends and being supported by said parallel discs.

vframe structure supported therein including parallel insulating discs, a plurality of parallel metallic laments extending across said frame structure, each filament being electrically connected to said frame at opposite ends, and an insulating member supported by said parallel discs at right angles thereto and supporting said iilaments at the center thereof.

4. A resistancedevice comprising a. vessel, a frame structure supported therein including parallel insulating discs having slots therein, a plurality of parallel metallic filaments extending across said frame structure, and a vertical spacer supporting said illaments intermediate their ends and having extendingportions fitted in the slots of said discs.

5. A resistance device comprising a vessel, a frame structure supported therein including parallel insulating discs, a mica strip supported by and in offset relation between said discs with respect to the axis thereof, said strip having locking slots on one edge, and a plurality of linear extensible metallic filaments supported horizontally on said frame, said iilaments being seated in said slots.

6. A resistance device comprising a vessel, a mount supported therein including insulating discs spaced apart in parallel relation and frame members connecting s ald discs, -a mica strip mounted in engaging relation with said discs and parallel to said frame members, said strip having a serrated edge substantially in a plane with said frame members, and a plurality of extensible heatable lament sections supported by said frame members and the serrated edge of said strip.

7. A resistance device comprising a vessel having a stem, leading-in wires ysealed in said stem, and a unitary mount supported on said stem 1ncluding parallel conducting members and spaced transverse insulating spacer members, a plurality of metallic laments arranged between said spacer members and attached to said conducting members, said leading-in wires projecting through one of said spacer members, and bridging connections between said conducting members and said leading-in wires adjacent the ends of said wires.

8. A resistance device comprising a vessel having a stem, leading-in wires sealed in said stem, and a unitary mount supported on said stem including parallel conducting members and transverse insulating spacer members, a. plurality of metallic laments arranged between said spacer members and attached to said conducting members, said leading-in wires projecting through one of said spacer members, bridging connections between said conducting members and said leadingin wires adjacent the ends of said wires, and a vertical spacer having a serrated edge engaging said laments and supported by said transverse spacers, said vertical spacer forming an insulating barrier between said leading-in wires.

JOHN W. WEST. 

